Nishijima Yasufumi, Ikeda Takeshi, Takamatsu Miwa, Kiso Yoshinobu, Shibata Hiroshi, Fushiki Tohru, Moritani Toshio
Institute for Health Care Science, Suntory Ltd., Osaka 618-8503, Japan.
Eur J Appl Physiol. 2002 Oct;87(6):475-80. doi: 10.1007/s00421-002-0678-1. Epub 2002 Aug 8.
The effects of caffeine ingestion on the activities of the autonomic nervous system (ANS) during endurance exercise at low intensity were investigated using a power spectrum analysis of heart rate variability. Placebo or caffeine (300 mg) capsules were randomly administered to the subjects. Each subject ingested the samples 2 h before cycling on an ergometer for 30 min at an intensity corresponding to 40%-50% of his ventilatory threshold. The electrocardiogram, blood pressure (BP) and gas exchange parameters were monitored during rest and exercise. The results indicated that there were no significant differences in heart rate and systolic blood pressure between the trials. The spectrum integrated values of the low frequency power and total power components in the caffeine trial were significantly greater than in the placebo trial during exercise, which implied that activities of the ANS were augmented by caffeine. Caffeine also induced enhanced lipid oxidation as shown by the significantly lower respiratory gas exchange ratio and increases in diastolic blood pressure during exercise. The results shed some light upon the relationship between the activity of the ANS, energy metabolism and BP. In conclusion, the results suggest that caffeinated beverages have a potential to be useful supplements to the prescription of exercise for individuals who experience a depressed activity of the ANS. The results also suggest that the experiment protocol used in this study is a sensitive and noninvasive method for evaluating the effects of various foods and nutrients on the activity of the ANS.
通过心率变异性的功率谱分析，研究了在低强度耐力运动期间摄入咖啡因对自主神经系统（ANS）活动的影响。向受试者随机给予安慰剂或咖啡因（300毫克）胶囊。每位受试者在功率自行车上以相当于其通气阈值40%-50%的强度骑行30分钟前2小时摄入样品。在休息和运动期间监测心电图、血压（BP）和气体交换参数。结果表明，各试验之间心率和收缩压无显著差异。运动期间，咖啡因试验中低频功率和总功率成分的频谱积分值显著高于安慰剂试验，这意味着咖啡因增强了ANS的活动。咖啡因还导致脂质氧化增强，表现为运动期间呼吸气体交换率显著降低和舒张压升高。这些结果为ANS活动、能量代谢和血压之间的关系提供了一些线索。总之，结果表明含咖啡因饮料有可能成为对ANS活动低下个体运动处方有用的补充剂。结果还表明，本研究中使用的实验方案是一种评估各种食物和营养物质对ANS活动影响的灵敏且无创的方法。
